This invention relates to crosslinkable-group-containing polyamic acids, melt-moldable or formable, crosslinkable-group-containing polyimides, production processes thereof, and crosslinked thermoplastic polyimides obtained by heat-treating them. Specifically, the present invention is concerned with crosslinked thermoplastic polyimides having various excellent properties inherent to polyimides, namely, high heat resistance, excellent mechanical properties, superb sliding property, low water absorption property, outstanding electrical properties, high thermal oxidation resistance, high chemical resistance and high radiation resistance, especially those improved more markedly in heat resistance, chemical resistance and mechanical properties, crosslinkable-group-containing polyimides which are thermoplastic and melt-moldable or formable, crosslinkable-group-containing polyamic acids as precursors of the crosslinkable-group-containing polyimides, production proceses thereof, and their solutions or suspensions.
Polyimides have been used widely for many years as molding or otherwise forming materials, composite materials, or electrical or electronic materials in various fields, because in addition to their superb heat resistance, they are also excellent in mechanical properties and electrical properties.
For example, a polyimide (xe2x80x9cKaptonxe2x80x9d, xe2x80x9cVespelxe2x80x9d, trade names; products of E.I. DuPont de Nemours and Co., Inc.) of the formula (A) is known as a representative polyimide: 
This polyimide is non-thermoplastic and is insoluble and infusible, and hence has a drawback in moldability or formability. It is therefore accompanied by a problem that no mass production is practically feasible. As a specific processing method, a block is obtained using a special molding process called powder sintering molding, and then, mechanical working such as cutting, grinding and polishing is applied to the block to obtain a formed product.
As an amorphous thermoplastic polyimide with improved moldability or formability, a polyetherimide represented by the formula (B) (xe2x80x9cUltemxe2x80x9d, trade name; product of General Electric Company) is known: 
However, this polyimide is soluble in amide-type aprotonic polar solvents and halogenated hydrocarbon solvents and is inferior in chemical resistance. In addition, its glass transition temperature is 215xc2x0 C., and a further improvement in heat resistance is desired depending on the application.
Further, a polyimide which is imparted with moldability or formability and is represented by the formula (C): 
shows melt fluidity at its melting point and higher and permits melt molding or forming while retaining the inherent properties of polyimides because it has a melting point at 385xc2x0 C. (U.S. Pat. No. 5,043,419). Although the glass transition temperature of this polyimide is relatively high, i.e., 250xc2x0 C., marked reductions in properties, which are accompanied by deformation, softening or the like, take place when used at the glass transition temperature or higher. Further improvements are therefore desired depending on its application. Further, this polyimide is inferior in chemical resistance especially under stress, and an improvement is strongly desired in this respect.
Since the properties of a thermoplastic polyimide depend on the backbone structure of the polyimide, a variety of polyimides are selected in view of their inherent performance such as heat resistance, moldability or formability, mechanical properties and chemical resistance. Nonetheless, one or more of these individual properties may be found to be insufficient depending on the application, leading to an outstanding desire for the improvement of the above-described various properties.
On the other hand, a variety of thermosetting polyimides are available on the market. As a representative example of these polyimides, a polyimide available from monomers represented by the formula (D): 
is known [xe2x80x9cKerimid-601xe2x80x9d, trade name; product of Rhone-Poulenc SA; F. D. Darmory, xe2x80x9cNational SAMPLE Symposiumxe2x80x9d, 19, 693 (1974)]. As this polyimide is thermosetting, it is less susceptible to deformation or softening than thermoplastic polyimides and therefore, can be used under high temperature condition. However, this polyimide is not high in mechanical properties, especially in toughness and is weak against external force such as an impact. Due to its thermosetting property, no melt molding or forming is feasible. It is therefore necessary to carry out shaping at the stage of a prepolymer before its hardening and then to conduct heat treatment.
For the purpose of making improvements in the detrimental mechanical properties of these thermosetting polyimides, it is known to use a linear polyimide as a backbone and then to introduce crosslinking members into its ends and/or substituent groups. Reference may be had, for example, to U. S. Pat. No. 5,138,028, U.S. Pat. No. 5,478,915, U.S. Pat. No. 5,493,002, U.S. Pat. No. 5,567,800, U.S. Pat. No. 5,644,022, U.S. Pat. No. 5,412,066, and U.S. Pat. No. 5,606,014.
As technical details, U.S. Pat. No. 5,567,800, for example, discloses thermosetting polyimides available from heat treatment of imide oligomers having carbon-carbon triple bonds at their molecule ends, which can in turn be obtained from monomers represented by the formula (E): 
and an end blocking agent, respectively. Although the polyimides disclosed in this patent have various excellent properties, they still do not permit melt molding or forming, and therefore, their molding or forming is limited to processing which makes use of solutions of polyamic acids as precursors. In general, subsequent to the shaping of a solution of a polyamic acid, removal of the solvent and a dehydrating imidation reaction are conducted by heating. As this processing involves the removal of the solvent, it is generally impossible to obtain a molded or formed product having a large thickness. This processing is therefore limited in shape to films or sheets, and further, involves problems such as foaming due to remaining solvent and a need for recovery of a great deal of solvent.
An object of the present invention is to provide crosslinkable-group-containing polyimides of various known thermoplastic polyimide backbone structures, which are provided with far better heat resistance, chemical resistance and mechanical properties than known polyimides of the structures without impairing advantages inherent to the structure, such as excellent moldability or formability, superb sliding property, low water absorption property, outstanding electrical properties, high thermal oxidation stability and high radiation resistance.
Specifically described, the terms xe2x80x9cheat resistancexe2x80x9d, xe2x80x9cchemical resistancexe2x80x9d and xe2x80x9cmechanical propertiesxe2x80x9d the improvements of which constitute one of themes sought for attainment by the present invention mean, for example, physical property values and test results such as those to be described below.
{circle around (1)} Concerning heat resistance, representative examples can include glass transition temperature; softening temperature, deflection temperature under load, and mechanical properties at high temperatures in thermal mechanical analyses; retentions of mechanical properties in thermal cycle tests; solder reflow heat resistance test; heat resistance test; and hot air aging test. Among these, the themes the attainment of which are sought for in the present invention can include especially deflection temperature under load, mechanical properties at high temperatures, retentions of mechanical properties in thermal cycle tests, and the like.
{circle around (2)} As to chemical resistance, representative examples can include solvent dissolution resistance test, solvent immersion test, under-stress solvent immersion resistance resistance test, and retentions of various physical properties after immersion in solvent under stress. Among these, the themes the attainment of which are sought for in the present invention can include especially under stress solvent immersion resistance test, retentions of various physical properties after immersion in solvent under stress, and the like.
{circle around (3)} In respect to mechanical properties, representative examples can include tensile test, compression test, bending test, Izod impact test, and fatigue test. Among these, the themes the attainment of which is sought for in the present invention can include especially yield strength, tensile modulus, flexural modulus, Izod impact value, and the like.
Describing in other words from another viewpoint, the themes the attainment of which is sought for by the present invention are to provide a crosslinkable-group-containing polyimide imparted with thermoplasticity by additionally providing it with high moldability or formability, which has not been brought about by conventional polyimides of the end-curing type, while retaining excellent physical properties inherent to thermosetting polyimides of the end-curing type, that is, superb sliding property, low water absorption property, outstanding electrical properties, high thermal oxidation stability, high chemical resistance and excellent mechanical properties.
Accordingly, an object of the present invention is to provide a crosslinkable-group-containing polyimide, which is thermoplastic and permits melt moldability or formability, or a crosslinkable-group-containing polyamic acid which is a precursor of the polyimide. Another object of the present invention is to provide its production process.
It is an important feature of the present invention that the crosslinkable-group-containing polyimide according to the present invention permits melt molding or forming despite its inclusion of crosslinkable groups, which allow a crosslinking reaction, and the crosslinkable-group-containing thermoplastic polyimide shows thermoplasticity. It is here that the crosslinkable-group-containing polyimide according to the present invention is totally different from the conventional thermosetting resins which are crosslinkable. The present invention is based on a novel concept never in existence to date, and has made it possible to achieve mutually contradictory matters of intermolecular crosslinking and melt fluidity.
To achieve the above-described objects, the present inventors have proceeded with an extensive investigation. As a result, it has found that a crosslinkable-group-containing polyimide molecule ends of which are blocked with 1 to 80 mole % of a crosslinkable-group-containing dicarboxylic acid anhydride and 99 to 20 mole % of a crosslinkable-group-free dicarboxylic acid anhydride can achieve the above-described objects and permits melt molding or forming despite it has been more significantly improved and is outstanding especially in heat resistance, chemical resistance and mechanical properties, leading to the completion of the present invention.
Described specifically, the present invention provides the following polyimides or processes (1)-(35):
(1) A crosslinkable-group-containing polyimide comprising crosslinkable groups at 1 to 80 mole % of molecule ends thereof.
(2) A crosslinkable-group-containing polyimide as described in claim 1, wherein a backbone structure which forms the polyimide is substantially provided with thermoplasticity.
(3) A crosslinkable-group-containing polyimide as described above under (1) or (2), said polyimide permitting melt molding or forming, wherein 1 to 80 mole % of the molecule ends are crosslinkable-group-containing molecule ends represented by the chemical formula (2a) and 99 to 20 mole % of the molecule ends are crosslinking-group-free molecule ends represented by the chemical formula (2b): 
wherein Y represents a trivalent aromatic group selected from the group consisting: 
wherein X represents a divalent linking group selected from the group consisting of a direct bond, a carbonyl group, a sulfone group, a sulfide group, an ether group, an isopropylidene group and a hexafluoroisopropylidene group; and 
wherein T represents a divalent aromatic group consisting of: 
wherein X represents a divalent linking group selected from the group consisting of a direct bond, a carbonyl group, a sulfone group, a sulfide group, an ether group, an isopropylidene group and a hexafluoroisopropylidene group.
(4) A crosslinkable-group-containing polyimide as described above under any one of (1)-(3), wherein the polyimide comprises polyimide molecules of a structure represented by the chemical formula (2c): 
wherein T, PI and Y are groups to be indicated next, respectively, that is,
T represents a divalent aromatic group selected from the group consisting of: 
xe2x80x83wherein X represents a divalent linking group selected from the group consisting of a direct bond, a carbonyl group, a sulfone group, a sulfide group, an ether group, an isopropylidene group and a hexafluoroisopropylidene group;
PI represents a polyimide backbone; and
Y represents a trivalent aromatic group selected from the group consisting of: 
xe2x80x83wherein X represents a divalent linking group selected from the group consisting of a direct bond, a carbonyl group, a sulfone group, a sulfide group, an ether group, an isopropylidene group and a hexafluoroisopropylidene group.
(5) A crosslinkable-group-containing polyimide as described above under (3) or (4), wherein in the chemical formula (2b) or (2c), T is the following chemical formula (2d): 
(6) A crosslinkable-group-containing polyimide as described above under any one (3)-(5), wherein in the chemical formula (2a) or (2c), Y is the following chemical formula (2e): 
(7) A crosslinkable-group-containing polyimide as described above under any one of (1)-(6), wherein a backbone of the polyimide has recurring structural units represented by the chemical formula (1): 
wherein Ar and R are groups to be described next, that is,
Ar represents a divalent aromatic group selected from the group consisting of: 
xe2x80x83wherein J represents a divalent linking group selected from the group consisting of a carbonyl group, an ether group, an isopropylidene group and a hexafluoroisopropylidene group, K represents a divalent linking group selected from the group consisting of a direct bond, a carbonyl group, a sulfone group, a sulfide group, an ether group, an isopropylidene group and a hexafluoroisopropylidene group, p and q each independently stand for 0 or 1, and a position of each bond, said position being unspecified, is a para-position or meta-position; and
R represents a tetravalent aromatic group selected from the group consisting of: 
xe2x80x83wherein G represents a divalent aromatic group selected from the group consisting of a direct bond, a carbonyl group, a sulfone group, a sulfide group, an ether group, an isopropylidene group, a hexafluoroisopropylidene group, a 3-oxyphenoxy group, a 4-oxyphenoxy group, a 4xe2x80x2-oxy-4-biphenoxy group and a 4-[1-(4-oxyphenyl)-1-methylethyl]phenoxy group.
(8) A crosslinkable-group-containing polyimide as described above under claim 7, wherein 50 to 100 mole % of the recurring structural units represented by the chemical formula. (1) are of a recurring unit structure represented by the chemical formula (1a): 
wherein G is a divalent aromatic group selected from the group consisting of a direct bond, a carbonyl group, a sulfone group, a sulfide group, an ether group, an isopropylidene group, a hexafluoroisopropylidene group, a 3-oxyphenoxy group, a 4-oxyphenoxy group, a 4xe2x80x2-oxy-4-biphenoxy group and a 4-[1-(4-oxyphenyl)-1-methylethyl]phenoxy group.
(9) A crosslinkable-group-containing polyimide as described above under (8), wherein in the chemical formula (1a), G is a 4xe2x80x2-oxy-4-biphenoxy group.
(10) A crosslinkable-group-containing polyimide as described above under (8), wherein in the chemical formula (1a), G is a 4-[1-(4-oxyphenyl)-1-methylethyl]phenoxy group.
(11) A crosslinkable-group-containing polyimide as described above under (7), wherein 50 to 100 mole % of the recurring structural units represented by the chemical formula (1) are of a recurring unit structure represented by the chemical formula (1b): 
wherein X and R are groups to be indicated next, respectively, that is,
X represents a divalent linking group selected from the group consisting of a direct bond, a carbonyl group, a sulfone group, a sulfide group, an ether group, an isopropylidene group and a hexafluoroisopropylidene group; and
R represents a tetravalent linking group selected from the group consisting of: 
xe2x80x83wherein G represents a divalent aromatic group selected from the group consisting of a direct bond, a carbonyl group, a sulfone group, a sulfide group, an ether group, an isopropylidene group, a hexafluoroisopropylidene group, a 3-oxyphenoxy group, a 4-oxyphenoxy group, a 4xe2x80x2-oxy-4-biphenoxy group and a 4-[l-(4-oxyphenyl)-1-methylethyl]phenoxy group, and a position of each bond, said position being unspecified, is a para-position or meta-position.
(12) A crosslinkable-group-containing polyimide as described above under (11), wherein in the chemical formula (1b),
X is an oxygen atom;
imido-bonded positions of two benzenes to which X is directly bonded are a m-position and a para-position, respectively; and
R is a 3,4,3xe2x80x2,4xe2x80x2-substituted biphenyl.
(13) A crosslinkable-group-containing polyimide as described above under (7), wherein among the recurring structural units represented by the chemical formula (1), 50 to 100 mole % are of a recurring unit structure represented by the chemical formula (1c): 
wherein X and R are groups to be indicated next, respectively, that is,
X represents a divalent linking group selected from the group consisting of a direct bond, a carbonyl group, a sulfone group, a sulfide group, an ether group, an isopropylidene group and a hexafluoroisopropylidene group; and
R represents a tetravalent linking group selected from the group consisting of: 
xe2x80x83wherein G represents a divalent aromatic group selected from the group consisting of a direct bond, a carbonyl group, a sulfone group, a sulfide group, an ether group, an isopropylidene group, a hexafluoroisopropylidene group, a 3-oxyphenoxy group, a 4-oxyphenoxy group, a 4xe2x80x2-oxy-4-biphenoxy group and a 4-[1-(4-oxyphenyl)-1-methylethyl]phenoxy group, and a position of each bond, said position being unspecified, is a para-position or meta-position.
(14) A crosslinkable-group-containing polyimide as described above under (13), wherein in the chemical formula (1c), X is an oxygen atom.
(15) A crosslinkable-group-containing polyimide as described above under (13), wherein in the chemical formula (1c),
X is an oxygen atom;
positions of a benzene ring, at which two Xs are directly bonded, respectively, are m-positions relative to each other;
bonded positions of each of two benzenes to each of which X and an imido group are directly bonded are p-positions relative to each other; and
R is a 3,4,3xe2x80x2,4xe2x80x2-substituted biphenyl.
(16) A crosslinkable-group-containing polyimide as described above under (7), wherein among the recurring structural units represented by the chemical formula (1), 50 to 100 mole % are of a recurring unit structure represented by the chemical formula (1e): 
wherein Q, Z and Rare groups to be indicated next, respectively, that is,
Q represents a divalent aromatic group selected from the group consisting of an ether group and an isopropylidene group;
Z represents a divalent aromatic group selected from the group consisting of a direct bond, a carbonyl group, a sulfone group, a sulfide group, an ether group, an isopropylidene group, a hexafluoroisopropylidene group, and 
R represents a tetravalent aromatic group selected from the group consisting of: 
xe2x80x83wherein G represents a divalent aromatic group selected from the group consisting of a direct bond, a carbonyl group, a sulfone group, a sulfide group, an ether group, an isopropylidene group, a hexafluoroisopropylidene group, a 3-oxyphenoxy group, a 4-oxyphenoxy group, a 4xe2x80x2-oxy-4-biphenoxy group and a 4-[1-(4-oxyphenyl)-1-methylethyl]phenoxy group, and a position of each bond, said position being unspecified, is a para-position or meta-position.
(17) A crosslinkable-group-containing polyimide as described above under (16), wherein in the chemical formula (1e),
Q is an oxygen atom; and
Z is at least one divalent group selected from the group consisting of a direct bond, a carbonyl group, a sulfone group, a sulfide group, an ether group, an isopropylidene group and a hexafluoroisopropylidene group.
(18) A crosslinkable-group-containing polyimide as described above under (16), wherein in the chemical formula (1e),
Q is an oxygen atom;
Z is a direct bond; and
R is a 1,2,4,5-substituted benzene.
(19) A process for the production of a melt-moldable or formable, crosslinkable-group-containing polyimide, 1 to 80 mole % of molecule ends of the polyimide being crosslinkable-group-containing molecule ends represented by a chemical formula (2a) and 99 to 20 mole % of the molecule ends being crosslinkable-group-free molecule ends represented by a chemical formula (2b), which comprises end-blocking ends of polyimide backbones by using dicarboxylic acid anhydrides represented by the chemical formula (3e) and the chemical formula (3b): 
wherein Y represents a trivalent aromatic group selected from the group consisting: 
wherein X represents a divalent linking group selected from the group consisting of a direct bond, a carbonyl group, a sulfone group, a sulfide group, an ether group, an isopropylidene group and a hexafluoroisopropylidene group; 
wherein T represents a divalent aromatic group consisting of: 
wherein X represents a divalent linking group selected from the group consisting of a direct bond, a carbonyl group, a sulfone group, a sulfide group, an ether group, an isopropylidene group and a hexafluoroisopropylidene group; 
wherein Y represents a trivalent aromatic group selected from the group consisting: 
wherein X represents a divalent linking group selected from the group consisting of a direct bond, a carbonyl group, a sulfone group, a sulfide group, an ether group, an isopropylidene group and a hexafluoroisopropylidene group; and 
wherein T represents a divalent aromatic group consisting of: 
wherein X represents a divalent linking group selected from the group consisting of a direct bond, a carbonyl group, a sulfone group, a sulfide group, an ether group, an isopropylidene group and a hexafluoroisopropylidene group.
(20) A process as described above under (19), wherein the dicarboxylic acid anhydrides represented by the chemical formula (3a) and the chemical formula (3b) are used in amounts represented, on a molar ratio basis, by the numerical formula [1]:
1/99xe2x89xa6the dicarboxylic acid anhydride represented by the chemical formula (3a)/the dicarboxylic acid anhydride represented by the chemical formula (3b)xe2x89xa680/20xe2x80x83xe2x80x83[1]

Y represents a trivalent aromatic group selected from the group consisting of: 
xe2x80x83wherein X represents a divalent linking group selected from the group consisting of a direct bond, a carbonyl group, a sulfone group, a sulfide group, an ether group, an isopropylidene group and a hexafluoroisopropylidene group. 
T represents a divalent aromatic group selected from the group consisting of: 
xe2x80x83wherein X represents a divalent linking group selected from the group consisting of a direct bond, a carbonyl group, a sulfone group, a sulfide group, an ether group, an isopropylidene group and a hexafluoroisopropylidene group.
(21) A process as described above under (19) or (20), wherein in the chemical formula (3a) and/or the chemical formula (3b), T is the chemical formula (2a) and/or Y is the chemical formula (2e): 
(22) A process as described above under any one of (19)-(21), wherein the polyimide backbones have been obtained by thermally and/or chemically imidating a polyamic acid obtained as a polyimide precursor by polymerizing a diamine component and a tetracarboxylic acid anhydride component.
(23) A process as described above under (22), wherein the diamine component is at least one diamine component selected from the group consisting of diamine components represented by the chemical formula (4):
H2Nxe2x80x94Arxe2x80x94NH2xe2x80x83xe2x80x83(4)
wherein Ar represents a divalent aromatic group selected from the group consisting of: 
wherein J represents a divalent linking group selected from the group consisting of a carbonyl group, an ether group, an isopropylidene group and a hexafluoroisopropylidene group, K represents a divalent linking group selected from the group consisting of a direct bond, a carbonyl group, a sulfone group, a sulfide group, an ether group, an isopropylidene group and a hexafluoroisopropylidene group, p and q each independently stand for 0 or 1, and a position of each bond, said position being unspecified, is a para-position or meta-position;
(24) A process as described above under (23), wherein of the diamine component represented by the chemical formula (4), 50 to 100 mole % are represented by the chemical formula (4c): 
wherein X represents a divalent linking group selected from the group consisting of a direct bond, a carbonyl group, a sulfone group, a sulfide group, an ether group, an isopropylidene group and a hexafluoroisopropylidene group, and a position of each bond, said position being unspecified, is a para-position or meta-position.
(25) A process as described above under (24), wherein in the chemical formula (4c), X is an oxygen atom.
(26) A process as described above under (24), wherein in the chemical formula (4c),
X is an oxygen;
positions of a benzene ring, at which two Xs are directly bonded, respectively, are m-positions relative to each other; and
bonded positions of each of two benzenes to each of which X and an amino group are directly bonded are p-positions relative to each other.
27. A process as described above under (24), wherein of the diamine component represented by the chemical formula (4): 50 to 100 mole % are represented by the chemical formula (4d): 
wherein X represents a divalent linking group selected from the group consisting of a direct bond, a carbonyl group, a sulfone group, a sulfide group, an ether group, an isopropylidene group and a hexafluoroisopropylidene group.
(28) A process as described above under (27), wherein in the chemical formula (4d), X is a direct bond.
(29) A process as described above under (22), wherein the tetracarboxylic acid dihydride component is represented by the chemical formula (5): 
wherein R represents a tetravalent linking group selected from the group consisting of: 
wherein G represents a divalent aromatic group selected from the group consisting of a direct bond, a carbonyl group, a sulfone group, a sulfide group, an ether group, an isopropylidene group, a hexafluoroisopropylidene group, a 3-oxyphenoxy group, a 4-oxyphenoxy group, a 4xe2x80x2-oxy-4-biphenoxy group and a 4-[l-(4-oxyphenyl)-1-methylethyl]phenoxy group.
(30) A crosslinkable-group-containing polyimide as described above under any one of (1)-(18), there is a temperature T [xc2x0 C.] which simultaneously satisfy the following numerical formulas [2] and [3]:
1xe2x89xa6MV30(T)/MV5(T)xe2x89xa610xe2x80x83xe2x80x83[2]
10xe2x89xa6MV5(T)xe2x89xa610,000xe2x80x83xe2x80x83[3]
where
MV5(T): melt viscosity [Paxc2x7sec] of the polyimide as measured under a desired constant shearing stress in a range of from 0.1 to 1 [MPa] after causing the polyimide to melt by holding the polyimide at a temperature T [xc2x0 C.] for 5 minutes; and
MV30(T): melt viscosity [Paxc2x7sec] of the polyimide as measured under the desired constant shearing stress in the range of from 0.1 to 1 [MPa] after causing the polyimide to melt by holding the polyimide at the temperature T [xc2x0 C.] for 30 minutes.
(31) A crosslinkable-group-containing polyimide as described above under any one of (1)-(18), wherein there is a temperature T [xc2x0 C.] which simultaneously satisfy the following numerical formulas [2], [3] and [4]:
1xe2x89xa6MV30(T)/MV5(T)xe2x89xa610xe2x80x83xe2x80x83[2]
10xe2x89xa6MV5(T)xe2x89xa610,000xe2x80x83xe2x80x83[3]
MV30(T+20)/MV5(T+20)xe2x89xa620xe2x80x83xe2x80x83[4]
where
MV5(T): melt viscosity [Paxc2x7sec] of the polyimide as measured under a desired constant shearing stress in a range of from 0.1 to 1 [MPa] after causing the polyimide to melt by holding the polyimide at a temperature T [xc2x0 C.] for 5 minutes;
MV5(T+20): melt viscosity [Paxc2x7sec] of the polyimide as measured under the desired constant shearing stress in the range of from 0.1 to 1 [MPa] after causing the polyimide to melt by holding the polyimide at a temperature T+20 [xc2x0 C.] for 5 minutes;
MV30(T): melt viscosity [Paxc2x7sec] of the polyimide as measured under the desired constant shearing stress in the range of from 0.1 to 1 [MPa] after causing the polyimide to melt by holding the polyimide at the temperature T [xc2x0 C.] for 30 minutes.
MV30(T+20): melt viscosity [Paxc2x7sec] of the polyimide as measured under the desired constant shearing stress in the range of from 0.1 to 1 [MPa] after causing the polyimide to melt by holding the polyimide at a temperature T+20 [] for 30 minutes.
(32) A crosslinkable-group-containing polyimide as described above under any one of (1)-(18), which simultaneously satisfies the following numerical formulas [5] and [6]:
xe2x80x831xe2x89xa6MV30(360)/MV5(360)xe2x89xa610xe2x80x83xe2x80x83[5]
10xe2x89xa6MV5(360)xe2x89xa610,000xe2x80x83xe2x80x83[6]
where
MV5(360): melt viscosity [Paxc2x7sec] of the polyimide as measured under a desired constant shearing stress in a range of from 0.1 to 1 [MPa] after causing the polyimide to melt by holding the polyimide at 360 [xc2x0 C.] for 5 minutes; and
MV30(360): melt viscosity [Paxc2x7sec] of the polyimide as measured under the desired constant shearing stress in the range of from 0.1 to 1 [MPa] after causing the polyimide to melt by holding the polyimide at 360 [xc2x0 C.] for 30 minutes.
(33) A crosslinkable-group-containing polyimide as described above under any one of (1)-(18), wherein a time t (min) which satisfies the numerical formula [7] lasts 10 minutes or longer:
Gxe2x80x2(t)=Gxe2x80x3(t)xe2x80x83xe2x80x83[7]
where
Gxe2x80x2 (t): storage modulus of the polyimide as measured at 360xc2x0 C. and 1 Hz after an elapse of the time t (min) and
Gxe2x80x3 (t): loss modulus of the polyimide as measured at 360xc2x0 C. and 1 Hz after an elapse of the time t (min).
(34) A crosslinked polyimide obtained by heat-treating a crosslinkable-group-containing polyimide as described above under any one of (1)-(18) and (30)-(33).
(35) A solution or suspension comprising a crosslinkable-group-containing polyimide as described above under any one of (1)-(18) and (30)-(33).
The polyimide according to the present invention is a crosslinkable-group-containing polyimide which contains crosslinking groups at 1 to 80 mole % of molecule ends thereof.
[Molecule Ends]
The term xe2x80x9cmolecule endsxe2x80x9d as used herein means molecule ends, which are not contained in recurring structural units of a polyimide molecule chain and schematically correspond to xe2x80x9c-Endxe2x80x9ds in the chemical formula (6a).
Where, as will be indicated by the chemical formula (6b), two kinds of units A and B exist in a recurring structural unit and the number of units of one kind (xe2x80x9cAxe2x80x9d in this case) is greater by one than that of the unit(s) of the other kind, molecule ends schematically corresponds to xe2x80x9c-Endxe2x80x9ds in the chemical formula (6b).
It is to be noted that the structural unit A or B is not supposed to be contained in the structure of each xe2x80x9c-Endxe2x80x9d. 
[Crosslinkable Groups]
The term xe2x80x9ccrosslinkable groupsxe2x80x9d means groups capable of forming a certain bond between molecule chains as a result of a reaction between crosslinkable groups or a crosslinkable group and a group on a polyimide backbone under specific crosslinking conditions. In the present invention, crosslinkable groups exist in molecule ends of polyimide chains.
No limitation is imposed on the crosslinking conditions, and a known crosslinking reaction such as heat-setting or photo-setting can be applied. From the standpoint of use, preferred are crosslinkable groups to which conditions not decomposing a polyimide backbone under crosslinking conditions are applicable.
If crosslinkable groups react with groups on a polyimide backbone, groups usable as the crosslinkable groups obviously differ depending on the polyimide backbone to be used.
As crosslinkable groups, those known to the public can be chosen and used as desired. No limitation is imposed on the kind of crosslinkable groups, but representative examples can include ethynyl groups, benzocyclobuten-4xe2x80x2-yl groups, vinyl groups, allyl groups, cyano groups, isocyanate groups, nitrilo groups, amino groups, isopropenyl groups, vinylene groups, vinylidene groups, ethynylidene groups, and biphenylenyl groups.
[Molecule Ends Having Preferred Crosslinkable Groups]
Molecule ends, each of which is usable in the present invention and has a crosslinkable group, are preferably those represented by the chemical formula (2a). The polyimide according to the present invention is characterized in that 1 to 80 mole % of the total number of end groups of the polymer chain are such crosslinkable-group-containing end groups and 99 to 20 mole % are crosslinkable-group-free end groups, preferably, those represented by the chemical formula (2b).
Specific examples of end structures represented by the chemical formula (2a) can include: 
Incidentally, the crosslinkable-group-containing end groups are not limited to those exemplified above, but known crosslinkable-group-containing end groups can be used either singly or in combination as desired.
As the most preferred crosslinkable-group-containing end group, one of the chemical formula (2a) in which Y is the chemical formula (2e) is used. Specifically, it is: 
[Crosslinkable-group-free Molecule Ends]
As the crosslinkable-group-containing polyimide according to the present invention is characterized in that it has crosslinkable groups at 1 to 80 mole % of its molecule ends, 99 to 20 mole % of its molecule ends are crosslinkable-group-free molecule ends. The term xe2x80x9ccrosslinkable-group-free molecule endsxe2x80x9d means molecule end groups which cannot for many bond between molecule chains because no reaction takes place between the molecule ends themselves or the molecule ends and groups on polyimide backbones under any conditions during a molding or forming step, a post treatment step or the like.
[Crosslinkable-group-containing Molecule Ends Which may Function as Crosslinkable-group-free Molecule Ends]
As the term xe2x80x9ccrosslinkable-group-free molecule endsxe2x80x9d as used herein means molecule end groups incapable of crosslinking under any conditions during a molding or forming step, a post treatment step or the like as described above, a structure which becomes a crosslinkable group under certain conditions can function as a crosslinkable-group-free group when employed under conditions milder than the first-mentioned conditions.
[Preferred Crosslinkable-group-free Molecule Ends]
As crosslinkable-group-free molecule ends, those of known structures can be used either singly or in combination, and no limitation is imposed. Nonetheless, use of those represented by the chemical formula (2) is preferred. Most preferably, those of the chemical formula (2) in which T represents the chemical formula (2d) are used. Specifically, it is: 
[Molar Ratio of Crosslinkable-group-containing Molecule Ends to Crosslinkable-group-free Molecule Ends]
The present invention relates to the crosslinkable-group-containing polyimide characterized in that it contains crosslinkable groups at 1 to 80 mole % of its molecule ends. It is therefore essential that the molar ratio of crosslinkable-group-containing molecule ends to crosslinkable-group-free molecule ends falls within the following range:
1/99xe2x89xa6[Exe2x80x21]/[Exe2x80x22]xe2x89xa680/20
where
[Exe2x80x21]: the molar quantity of the crosslinkable-group-containing molecule ends; and
[Exe2x80x22]: the molar quantity of the crosslinkable-f-group-free molecule ends.
If the value of [Exe2x80x21]/[Exe2x80x22] falls short of this range and is smaller than 1/99, no sufficient crosslinking density can be achieved, leading to insufficient improvements in chemical resistance, heat resistance and mechanical properties. If the value of [Exe2x80x21]/[Exe2x80x22] is greater than 80/20, on the other hand, a sufficient crosslinking density is available, but upon melt molding or forming, a substantial viscosity increase takes place so that the melt molding or forming becomes infeasible.
The range of the [Exe2x80x21]/[Exe2x80x22] value has to be chosen appropriately depending on molding or forming conditions. In general, however, the preferred range is:
5/95xe2x89xa6[Exe2x80x21]/[Exe2x80x22]xe2x89xa670/30,
and the more preferred range is:
10/90xe2x89xa6[Exe2x80x21]/[Exe2x80x22]xe2x89xa670/30.
The still more preferred range varies depending on the molding or forming process. For example, in a batchwise molding or forming process, such as compression molding, that involves residence in a molten state, the still more preferred range is:
30/70xe2x89xa6[Exe2x80x21]/[Exe2x80x22]xe2x89xa670/30,
and the most preferred range is:
40/60xe2x89xa6[Exe2x80x21]/[Exe2x80x22]xe2x89xa660/40.
For example, in a molding or forming process, such as injection molding or extrusion, that involves residence in a molten state and requires a continuous operation, the preferred range is:
10/90xe2x89xa6[Exe2x80x21]/[Exe2x80x22]xe2x89xa650/50,
and the most preferred range is:
20/80xe2x89xa6[Exe2x80x21]/[Exe2x80x22]xe2x89xa640/60.
For example, in a molding or forming process that does not involve much residence in a molten state, the preferred range is:
20/80xe2x89xa6[Exe2x80x21]/[Exe2x80x22]xe2x89xa660/40,
and the most preferred range is:
30/70xe2x89xa6[Exe2x80x21]/[Exe2x80x22]xe2x89xa650/50.
[Structure of the Crosslinkable-group-containing Polyimide]
To form the backbone structure of the crosslinkable-group-containing polyimide according to the present invention, known polyimides are used singly, as a blend of a desired ratio, or as a copolymer of a desired ratio.
[Structure of Preferred Crosslinkable-group-containing Polyimidexe2x80x94(1)]
Although no limitation is imposed on the backbone structure of the crosslinkable-group-containing polyimide according to the present invention, preferred is a crosslinkable-group-containing polyimide characterized in that the backbone structure, which makes up the crosslinkable-group-containing polyimide, is substantially provided with thermoplasticity.
[What Does xe2x80x9cSubstantially Provided With Thermoplasticityxe2x80x9d Mean?]
The expression xe2x80x9ca backbone structure is substantially provided with thermoplasticityxe2x80x9d as used herein means that plasticity is shown as a characteristic property of the backbone structure, specifically that a polyimide, which has been obtained by polymerizing a polyimide of the backbone structure under diamine-excess conditions and then blocking molecular chains of the polyimide at ends thereof with phthalic anhydride in a stoichiometric or greater amount, shows thermoplasticity.
[Structure of Preferred Crosslinkable-group-containing Polyimidexe2x80x94(2)]
Preferably, the polyimide is a crosslinkable-group-containing polyimide which permits melt molding or forming.
[Melt Molding or Forming]
The term xe2x80x9cmelt molding or formingxe2x80x9d as used herein means a molding or forming process of the polyimide, in at least one step of which the resin is caused to flow in a molten state. The molten state of the polyimide can be achieved only at a temperature higher than its crystal melting temperature or glass transition temperature. To allow a resin to flow, the resin is required to have an adequate melt viscosity which varies depending on shearing stress which in turn differs depending on the molding or forming process. Incidentally, the temperature, shearing stress and melt viscosity differ depending on the molding or forming process.
Illustrative of the molding or forming process are extrusion, injection molding, compression molding, blow molding, vacuum forming, rotational molding, reaction injection molding, laminated molding, and casting.
[Variations in Melt Viscosity]
To continuously perform processing under steady state, variations in melt viscosity are required to be small. The term xe2x80x9cvariations in melt viscosityxe2x80x9d means variations in viscosity when a resin is held at a processing temperature under processing shearing stress.
[Melt Viscosity]
From the foregoing, the polyimide according to the present invention is a crosslinkable-group-containing polyimide which, although no limitation is imposed on its viscosity, preferably satisfies the following numerical formulas [2] and [3] simultaneously:
1xe2x89xa6MV30(T)/MV5(T)xe2x89xa610xe2x80x83xe2x80x83[2]
10xe2x89xa6MV5(T)xe2x89xa610,000xe2x80x83xe2x80x83[3]
where
MV5(T): melt viscosity [Paxc2x7sec] of the polyimide as measured under a desired constant shearing stress in a range of from 0.1 to 1 [MPa] after causing the polyimide to melt by holding the polyimide at a temperature T [xc2x0 C.] for 5 minutes, and
MV30(T): melt viscosity [Paxc2x7sec] of the polyimide as measured under the desired constant shearing stress in the range of from 0.1 to 1 [MPa] after causing the polyimide to melt by holding the polyimide at the temperature T [xc2x0 C.] for 30 minutes;
more preferably, satisfies the following numerical formulas [2], [3] and [4] simultaneously:
1xe2x89xa6MV30(T)/MV5(T)xe2x89xa610xe2x80x83xe2x80x83[2]
10xe2x89xa6MV5(T)xe2x89xa610,000xe2x80x83xe2x80x83[3]
MV30(T+20)/MV5(T+20)xe2x89xa620xe2x80x83xe2x80x83[4]
where
MV5(T): melt viscosity [Paxc2x7sec] of the polyimide as measured under a desired constant shearing stress in a range of from 0.1 to 1 [MPa] after causing the polyimide to melt by holding the polyimide at a temperature T [xc2x0 C.] for 5 minutes,
MV5(T+20): melt viscosity [Paxc2x7sec] of the polyimide as measured under the desired constant shearing stress in the range of from 0.1 to 1 [MPa] after causing the polyimide to melt by holding the polyimide at a temperature T+20 [xc2x0 C.] for 5 minutes,
MV30(T): melt viscosity [Paxc2x7sec] of the polyimide as measured under the desired constant shearing stress in the range of from 0.1 to 1 [MPa] after causing the polyimide to melt by holding the polyimide at the temperature T [xc2x0 C.] for 30 minutes, and
MV30(T+20): melt viscosity [Paxc2x7sec] of the polyimide as measured under the desired constant shearing stress in the range of from 0.1 to 1 [MPa] after causing the polyimide to melt by holding the polyimide at a temperature T+20 [xc2x0 C.] for 30 minutes; and
most preferably, satisfies the following numerical formulas [2], [3] and [4b] simultaneously:
1xe2x89xa6MV30(T)/MV5(T)xe2x89xa610xe2x80x83xe2x80x83[2]
10xe2x89xa6MV5(T)xe2x89xa610,000xe2x80x83xe2x80x83[3]
MV30(T+20)/MV5(T+20)xe2x89xa610xe2x80x83xe2x80x83[4b]
xe2x80x83where
MV5(T): melt viscosity [Paxc2x7sec] of the polyimide as measured under a desired constant shearing stress in a range of from 0.1 to 1 [MPa] after causing the polyimide to melt by holding the polyimide at a temperature T [xc2x0 C.] for 5 minutes,
MV5(T+20): melt viscosity [Paxc2x7sec] of the polyimide as measured under the desired constant shearing stress in the range of from 0.1 to 1 [MPa] after causing the polyimide to melt by holding the polyimide at a temperature T+20 [xc2x0 C.] for 5 minutes,
MV30(T): melt viscosity [Paxc2x7sec] of the polyimide as measured under the desired constant shearing stress in the range of from 0.1 to 1 [MPa] after causing the polyimide to melt by holding the polyimide at the temperature T [xc2x0 C.] for 30 minutes, and
MV30(T+20): melt viscosity [Paxc2x7sec] of the polyimide as measured under the desired constant shearing stress in the range of from 0.1 to 1 [MPa] after causing the polyimide to melt by holding the polyimide at a temperature T+20 [xc2x0 C.] for 30 minutes.
When as crosslinkable-group-containing end groups, those of the structure represented by the chemical formula (2) are used, inclusion of 360xc2x0 C. within a range of the temperature T [xc2x0 C.] which satisfies the above numerical formulas [2], [3], [4] and [4b] is preferred from the additional consideration of the fact that the crosslinking temperature condition for the crosslinkable groups is about 360xc2x0 C. or higher.
In other words, the polyimide according to the present invention is a crosslinkable-group-containing polyimide which preferably satisfies the following numerical formulas [5] and [6] simultaneously:
1xe2x89xa6MV30(360)/MV5(360)xe2x89xa610xe2x80x83xe2x80x83[5]
10xe2x89xa6MV5(360)xe2x89xa610,000xe2x80x83xe2x80x83[6]
where
MV5(360): melt viscosity [Paxc2x7sec] of the polyimide as measured under a desired constant shearing stress in a range of from 0.1 to 1 [MPa] after causing the polyimide to melt by holding the polyimide at 360 [xc2x0 C.] for 5 minutes, and
MV30(360): melt viscosity [Paxc2x7sec] of the polyimide as measured under the desired constant shearing stress in the range of from 0.1 to 1 [MPa] after causing the polyimide to melt by holding the polyimide at 360 [xc2x0 C.] for 30 minutes;
more preferably, satisfies the following numerical formulas [5], [6] and [8] simultaneously:
1xe2x89xa6MV30(360)/MV5(360)xe2x89xa610xe2x80x83xe2x80x83[5]
10xe2x89xa6MV5(360)xe2x89xa610,000xe2x80x83xe2x80x83[6]
MV30(380)/MV5(380)xe2x89xa620xe2x80x83xe2x80x83[8]
xe2x80x83where
MV5(360): melt viscosity [Paxc2x7sec] of the polyimide as measured under a desired constant shearing stress in a range of from 0.1 to 1 [MPa] after causing the polyimide to melt by holding the polyimide at 360 [xc2x0 C.] for 5 minutes,
MV5(380): melt viscosity [Paxc2x7sec] of the polyimide as measured under the desired constant shearing stress in the range of from 0.1 to 1 [MPa] after causing the polyimide to melt by holding the polyimide at 380 [xc2x0 C.] for 5 minutes,
MV30(360): melt viscosity [Paxc2x7sec] of the polyimide as measured under the desired constant shearing stress in the range of from 0.1 to 1 [MPa] after causing the polyimide to melt by holding the polyimide at 360 [xc2x0 C.] for 30 minutes,
MV30(380): melt viscosity [Paxc2x7sec] of the polyimide as measured under the desired constant shearing stress in the range of from 0.1 to 1 [MPa] after causing the polyimide to melt by holding the polyimide at 380 [xc2x0 C.] for 30 minutes; and
most preferably, satisfies the following numerical formulas [5], [6] and [8b] simultaneously:
1xe2x89xa6MV30(360)/MV5(360)xe2x89xa610xe2x80x83xe2x80x83[5]
10xe2x89xa6MV5(360)xe2x89xa610,000xe2x80x83xe2x80x83[6]
MV30(380)/MV5(380)xe2x89xa610xe2x80x83xe2x80x83[8b]
xe2x80x83where
MV5(360): melt viscosity [Paxc2x7sec] of the polyimide as measured under a desired constant shearing stress in a range of from 0.1 to 1 [MPa] after causing the polyimide to melt by holding the polyimide at 360 [xc2x0 C.] for 5 minutes,
MV5(380): melt viscosity [Paxc2x7sec] of the polyimide as measured under the desired constant shearing stress in the range of from 0.1 to 1 [MPa] after causing the polyimide to melt by holding the polyimide at 380 [xc2x0 C.] for 5 minutes,
MV30(360): melt viscosity [Paxc2x7sec] of the polyimide as measured under the desired constant shearing stress in the range of from 0.1 to 1 [MPa] after causing the polyimide to melt by holding the polyimide at 360 [xc2x0 C.] for 30 minutes,
MV30(380): melt viscosity [Paxc2x7sec] of the polyimide as measured under the desired constant shearing stress in the range of from 0.1 to 1 [MPa] after causing the polyimide to melt by holding the polyimide at 380 [xc2x0 C.] for 30 minutes.
[Measuring Method of Melt Viscosity]
Although no particular limitation is imposed on the measuring method of a melt viscosity, the melt viscosity can be measured, for example, by a Koka-type flow tester (e.g., xe2x80x9cCFT500Axe2x80x9d manufactured by Shimadzu Corporation) under conditions of an orifice of 1.0 mm (diameter)xc3x9710 mm (length) and a load of 100 kgf.
It is known (from xe2x80x9cRheology Measuring Methodsxe2x80x9d compiled by the Rheology Committee of the Society of Polymer Science, Japanese) that in this case, shearing stress (Tw) [Pa] is determined by calculating apparent shear stress against a nozzle wall and the value so calculated is expressed by:
Tw=Pxc3x97R/2Lc
where
P: extrusion pressure [Pa];
R: nozzle diameter/2 [cm]; and
Lc: nozzle length [cm].
The shear stress measured by this measuring method is, therefore, 0.245 [MPa].
[Gel Time]
As another parameter which also indicates whether or not a melt flow is feasible, gel time can be mentioned. The gel time of a resin at a given temperature is represented by t which satisfies the following numerical formula [7]:
Gxe2x80x2(t)=Gxe2x80x3(t)xe2x80x83xe2x80x83[7]
where
Gxe2x80x2 (t): storage modulus of the resin as measured at the given temperature and a constant frequency after an elapse of the time t [min]; and
Gxe2x80x3 (t): loss modulus of the resin as measured at the given temperature and the constant frequency after an elapse of the time t (min).
No limitation is imposed on the gel time, because upon measuring the gel time, the sample temperature and the measuring frequency must be changed depending on the processing method and the properties of the resin. In the case of each polyimide in this application, however, the gel time measured at a constant sample temperature of 360xc2x0 C. and 1 Hz may preferably be 10 [min] or longer, with 20 [min] or longer being more preferred.
No particular limitation is imposed on the measuring methods of the storage modulus and loss modulus. As an example, however, they can be measured by a melt viscoelasticity meter (e.g., xe2x80x9cRDS-IIxe2x80x9d manufactured by Rheometrix Scientific F.E.) equipped with parallel plates (e.g., 25 mm disposable).
[Preferred Structure of Crosslinkable-group-containing Polyimidexe2x80x94(3)]
More preferably, the crosslinkable-group-containing polyimide according to the present invention is a crosslinkable-group-containing polyimide containing molecule chains each of which has a crosslinkable-group-containing end at an end thereof and a crosslinkable-group-free end at an opposite end thereof. Although no limitation is imposed on the content of the molecule-chains, their content may be preferably 0.2 mole % or higher, more preferably 1 mole % or higher, most preferably 5 mole % or higher.
The crosslinkable-group-containing polyimidexe2x80x94which is characterized in that it contains molecule chains, each of which has a crosslinkable-group-containing end at an end thereof and a crosslinkable-group-free end at an opposite end thereofxe2x80x94may more preferably be a crosslinkable-group-containing polyimide having the structure represented by the chemical formula (2c). Although no limitation is imposed on the content of the molecule chains in the polyimide either, their content may be preferably 0.2 mole % or higher, more preferably 1 mole % or higher, most preferably 5 mole % or higher.
[Preferred Structure of Crosslinkable-group-containing Polyimidexe2x80x94(4)]
The crosslinkable-group-containing polyimide according to the present invention may preferably contain recurring structural units represented by the chemical formula (1) in the polyimide backbone.
[More Preferred Structure of Crosslinkable-group-containing Polyimidexe2x80x94(1)]
One of more preferred examples of the crosslinkable-group-containing polyimide according to the present invention which has recurring structural units represented by the chemical formula (1) is characterized in that 50 to 100 mole % of the recurring structural units are recurring structural units represented by the chemical formula (1a).
Among these, most preferred are crosslinkable-group-containing polyimides 50 to 100 mole % of the recurring structural units of each of which have one of the following structures: 
[More Preferred Structure of Crosslinkable-group-containing Polyimidexe2x80x94(2)]
Another one of the more preferred examples of the crosslinkable-group-containing polyimide according to the present invention which has recurring structural units represented by the chemical formula (1) is characterized in that 50 to 100 mole % of the recurring structural units are recurring structural units represented by the chemical formula (1b).
Among these, most preferred are crosslinkable-group-containing polyimides 50 to 100 mole % of the recurring structural units of each of which have the following structure: 
[More Preferred Structure of Crosslinkable-group-containing Polyimidexe2x80x94(3)]
A further one of the more preferred examples of the crosslinkable-group-containing polyimide according to the present invention which has recurring structural units represented by the chemical formula (1) is characterized in that 50 to 100 mole % of the recurring structural units are recurring structural units represented by the chemical formula (1c).
Among these, preferred are crosslinkable-group-containing polyimides 50 to 100 mole % of the recurring structural units of each of which has the chemical formula (1c) in which X is an oxygen atom, and most preferred are crosslinkable-group-containing polyimides 50 to 100 mole % of the recurring structural units of each of which has a structure represented by: 
[More Preferred Structure of Crosslinkable-group-containing Polyimidexe2x80x94(4)]
A still further one of the more preferred examples of the crosslinkable-group-containing polyimide according to the present invention which has recurring structural units represented by the chemical formula (1) is characterized in that 50 to 100 mole % of the recurring structural units are recurring structural units represented by the chemical formula (1e).
Among these, preferred are crosslinkable-group-containing polyimides 50 to 100 mole % of the recurring structural units of each of which are recurring structural units represented by the following formula (1d): 
wherein X and R are groups to be indicated next, respectively, that is,
X represents a divalent linking group selected from the group consisting of a direct bond, a carbonyl group, a sulfone group, a sulfide group, an ether group, an isopropylidene group and a hexafluoroisopropylidene group; and
R represents a tetravalent aromatic group selected from the group consisting of: 
xe2x80x83wherein G represents a divalent aromatic group selected from the group consisting of a direct bond, a carbonyl group, a sulfone group, a sulfide group, an ether group, an isopropylidene group, a hexafluoroisopropylidene group, a 3-oxyphenoxy group, a 4-oxyphenoxy group, a 4xe2x80x2-oxy-4-biphenoxy group and a 4-[1-(4-oxyphenyl)-1-methylethyl]phenoxy group, and a position of each bond, said position being unspecified, is a para-position or meta-position.
Among these, preferred are crosslinkable-group-containing polyimides 50 to 100 mole % of the recurring structural units of each of which has the chemical formula (1d) in which Z2 is an oxygen atom, and most preferred are crosslinkable-group-containing polyimides 50 to 100 mole % of the recurring structural units of each of which has a recurring unit structure represented by: 
[Molecular Weight of Crosslinkable-group-containing Polyimide]
As a measure of the molecular weight of a crosslinkable-group-containing polyimide, a logarithmic viscosity number is used.
[Logarismic Viscosity Number of Crosslinkable-group-containing Polyimide]
The logarithmic viscosity number of a crosslinkable-group-containing polyimide is in a range of from 0.1 to 1.5 dL/g. A logarithmic viscosity number smaller than 0.1 leads to a decrease in the molecular weight between crosslinking points and hence to substantial reductions in mechanical properties, while a logarithmic viscosity number higher than 1.5 leads to an increase in melt viscosity and thus to a considerable reduction in melt moldability or formability. The preferred logarithmic viscosity number is in a range of from 0.2 to 1.2, with a range of from 0.3 to 0.8 being more preferred, and a range of from 0.4 to 0.6 being most preferred.
[Measuring Method of Logarithmic Viscosity Number]
The above-described logarithmic viscosity number can be measuring in a 9:1 by weight mixed solvent of p-chlorophenol and phenol, at a solution viscosity of 0.5 g/100 mL and 35xc2x0 C., by using, for example, a Ubbellohde viscometer.
[Regularity When the Crosslinkable-group-containing Polyimide is a Copolymer]
When the crosslinkable-group-containing polyimide according to the present invention is a copolymer, a limitation may be imposed or may not be imposed on the specific order or regularity of recurring units of two or more kinds which make up the copolymer. Concerning the kind of the copolymer, the copolymer can be of any one of random, alternating and block structures.
[Production Process of Crosslinkable-group-containing Polyimide]
A detailed description will hereinafter be made of the process for the production of the crosslinkable-group-containing polyimide according to the present invention. However, it should be borne in mind that no limitation is imposed on the production process in the present invention.
[Raw Materials to be Used]
The crosslinkable-group-containing polyimide according to the present invention is generally obtained from the following raw materials:
(A) a diamine component;
(B) a tetracarboxylic acid dianhydride component;
(C) an end blocking agent having a crosslinkable group; and
(D) an end blocking agent having no crosslinkable group.
[Diamine Component]
The diamine component usable to obtain the crosslinkable-group-containing polyimide according to the present invention can preferably be, but is not limited to, an aromatic diamine.
Examples of the diamine component can include:
a) Diamines containing one benzene ring:
p-phenylenediamine, and
m-phenylenediamine;
b) Diamines containing two benzene rings:
3,3xe2x80x2-diaminodiphenyl ether,
3,4xe2x80x2-diaminodiphenyl ether,
4,4xe2x80x2-diaminodiphenyl ether,
3,3xe2x80x2-diaminodiphenyl sulfide,
3,4xe2x80x2-diaminodiphenyl sulfide,
4,4xe2x80x2-diaminodiphenyl sulfide,
3,3xe2x80x2-diaminodiphenyl sulfone,
3,4xe2x80x2-diaminodiphenyl sulfone,
4,4xe2x80x2-diaminodiphenyl sulfone,
3,3xe2x80x2-diaminobenzophenone,
4,4xe2x80x2-diaminobenzophenone,
3,4xe2x80x2-diaminobenzophenone,
3,3xe2x80x2-diaminodiphenylmethane,
4,4xe2x80x2-diaminodiphenylmethane,
3,4xe2x80x2-diaminodiphenylmethane,
2,2-di(3-aminophenyl)propane,
2,2-di(4-aminophenyl)propane,
2-(3-aminophenyl)-2-(4-aminophenyl)propane,
2,2-di(3-aminophenyl)-1,1,1,3,3,3,-hexafluoropropane,
2,2-di(4-aminophenyl)-1,1,1,3,3,3,-hexafluoropropane,
2-(3-aminophenyl)-2-(4-aminophenyl)-1,1,1,3,3,3,-hexafluoropropane,
1,1-di(3-aminophenyl)-1-phenylethane,
1,1-di(4-aminophenyl)-1-phenylethane, and
1-(3-aminophenyl)-1-(4-aminophenyl)-1-phenylethane;
c) Diamines containing three benzene rings:
1,3-bis(3-aminophenoxy)benzene,
1,3-bis(4-aminophenoxy)benzene,
1,4-bis(3-aminophenoxy)benzene,
1,4-bis(4-aminophenoxy)benzene,
1,3-bis(3-aminobenzoyl)benzene,
1,3-bis(4-aminobenzoyl)benzene,
1,4-bis(3-aminobenzoyl)benzene,
1,4-bis(4-aminobenzoyl)benzene,
1,3-bis(3-amino-xcex1,xcex1-dimethylbenzyl)benzene,
1,3-bis(4-amino-xcex1,xcex1-dimethylbenzyl)benzene,
1,4-bis(3-amino-xcex1,xcex1-dimethylbenzyl)benzene,
1,4-bis(4-amino-xcex1,xcex1-dimethylbenzyl)benzene,
1,3-bis(3-amino-xcex1,xcex1-ditrifluoromethylbenzyl)-benzene,
1,3-bis(4-amino-xcex1,xcex1-ditrifluoromethylbenzyl)-benzene,
1,4-bis(3-amino-xcex1,xcex1-ditrifluoromethylbenzyl)-benzene,
1,4-bis(4-amino-xcex1,xcex1-ditrifluoromethylbenzyl)-benzene,
2,6-bis(3-aminophenoxy)benzonitrile, and
2,6-bis(3-aminophenoxy)pyridine;
d) Diamines containing four benzene rings:
4,4xe2x80x2-bis(3-aminophenoxy)biphenyl,
4,4xe2x80x2-bis(4-aminophenoxy)biphenyl,
bis[4-(3-aminophenoxy)phenyl]ketone,
bis[4-(4-aminophenoxy)phenyl]ketone,
bis[4-(3-aminophenoxy)phenyl]sulfide,
bis[4-(4-aminophenoxy)phenyl]sulfide,
bis[4-(3-aminophenoxy)phenyl]sulfone,
bis[4-(4-aminophenoxy)phenyl]sulfone,
bis[4-(3-aminophenoxy)phenyl]ether,
bis[4-(4-aminophenoxy)phenyl]ether,
2,2-bis[4-(3-aminophenoxy)phenyl]propane,
2,2-bis[4-(4-aminophenoxy)phenyl]propane,
2,2-bis[3-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, and
2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane;
e) Diamines containing five benzene rings:
1,3-bis[4-(3-aminophenoxy)benzoyl]benzene,
1,3-bis[4-(4-aminophenoxy)benzoyl]benzene,
1,4-bis[4-(3-aminophenoxy)benzoyl]benzene,
1,4-bis[4-(4-aminophenoxy)benzoyl]benzene,
1,3-bis[4-(3-aminophenoxy)-xcex1,xcex1-dimethylbenzyl]benzene,
1,3-bis [4-(4-aminophenoxy)-xcex1,xcex1-dimethylbenzyl]benzene,
1,4-bis[4-(3-aminophenoxy)-xcex1,xcex1-dimethylbenzyl]benzene, and
1,4-bis[4-(4-aminophenoxy)-xcex1,xcex1-dimethylbenzyl]benzene;
f) Diamines containing six benzene rings:
4,4xe2x80x2-bis[4-(4-aminophenoxy)benzoyl]diphenyl ether,
4,4xe2x80x2-bis[4-(4-amino-xcex1,xcex1-dimethylbenzyl)phenoxy]benzophenone,
4,4xe2x80x2-bis[4-(4-amino-xcex1,xcex1-dimethylbenzyl)phenoxy]diphenyl sulfone, and
4,4xe2x80x2-bis[4-(4-aminophenoxy)phenoxy]diphenyl sulfone;
g) Diamines containing aromatic substituent group(s):
3,3xe2x80x2-diamino-4,4xe2x80x2-diphenoxybenzophenone,
3,3xe2x80x2-diamino-4,4xe2x80x2-dibiphenoxybenzophenone,
3,3xe2x80x2-diamino-4-phenoxybenzophenone, and
3,3xe2x80x2-diamino-4-biphenoxybenzophenone; and
h) Diamines containing a spirobiindane ring:
6,6xe2x80x2-bis(3-aminophenoxy)3,3,3xe2x80x2,3xe2x80x2-tetramethyl-1,1xe2x80x2-spirobiindane, and
6,6xe2x80x2-bis(4-aminophenoxy)3,3,3xe2x80x2,3xe2x80x2-tetramethyl-1,1-spirobiindane.
Also usable are diamines each of which is obtained by substituting some or all of the hydrogen atoms on one or more of the aromatic ring(s) of the corresponding one of the above-described diamines by a like number of substituent group(s) selected from fluoro, methyl, methoxy, trifluoromethyl or trifluoromethoxy groups.
Further, these diamines are also usable after in place of some or all of the hydrogen atoms on one or more of the aromatic ring(s) of each of the diamines, a like number of ethynyl group(s), benzocyclobuten-4xe2x80x2-yl group(s), vinyl group(s), allyl group(s), cyano group(s), isocyanate group(s), nitrilo group(s) and/or isopropenyl group(s), which can act as crosslinking points, are introduced as substituent group (s), preferably to an extent not impairing the moldability or formability. Moreover, one or more of vinylene groups, vinylidene groups and ethynylidene groups, which can act as crosslinking points, can be incorporated into each backbone skeleton, rather than as substituent group(s), preferably to an extent not impairing the moldability or formability.
In addition, for the purpose of achieving improvements in or modifications to performance, copolymerization can be conducted using one or more aliphatic diamines, to an extent not impairing various good physical properties, together with the above-described diamine. Examples of such aliphatic diamines can include:
i) Siloxanediamines:
1,3-bis(3-aminopropyl)tetramethyldisiloxane,
1,3-bis(4-aminobutyl)tetramethyldisiloxane,
xcex1,xcfx89-bis(3-aminopropyl)polydimethylsiloxane, and
xcex1,xcfx89-bis(3-aminobutyl)polydimethylsiloxane;
j) Ethyleneglycoldiamines:
bis(aminomethyl) ether,
bis(2-aminoethyl) ether,
bis(3-aminopropyl) ether,
bis(2-aminomethoxy)ethyl]ether,
bis[2-(2-aminoethoxy)ethyl]ether,
bis[2-(3-aminoprotoxy)ethyl]ether,
1,2-bis(aminomethoxy)ethane,
1,2-bis(aminoethoxy)ethane,
1,2-bis[2-(aminomethoxy)ethoxy]ethane,
1,2-bis[-2-(2-aminomethoxy)ethoxy]ethane,
ethylene glycol bis(3-aminopropyl) ether,
diethylene glycol bis(3-aminopropyl) ether, and
triethylene glycol bis(3-aminopropyl) ether;
k) Methylenediamines:
1,3-diaminopropane,
1,4-diaminobutane,
1,5-diaminopentane,
1,6-diaminohexane,
1,7-diaminoheptane,
1,8-diaminooctane,
1,9-diaminononane,
1,10-diaminodecane,
1,11-diaminoundecane, and
1,12-diaminododecane; and
l) Alicyclic diamines:
1,2-diaminocyclohexane,
1,3-diaminocyclohexane,
1,4-diaminocyclohexane,
1,2-di(2-aminoethyl)cyclohexane,
1,3-di(2-aminoethyl)cyclohexane,
1,4-di(2-aminoethyl)cyclohexane,
bis(4-aminocyclohexyl)methane,
2,6-bis(aminomethyl)bicyclo[2.2.1]heptane, and
2,5-bis(aminomethyl)bicyclo[2.2.1]heptane.
These diamines can be used either singly or in combination as needed.
[Preferred Diamine Components]
Among the above-exemplified diamine components, preferred diamines are those represented by the chemical formula (4).
[More Preferred Diamine Components (1)]
Among the diamines represented by the chemical formula (4), diamines of a more preferred type are those represented by the chemical formula (4c). When these more preferred diamine components are used, it is particularly preferred to use them in a proportion of 50 to 100 mole %.
Usable examples of the diamines represented by the chemical formula (4c) can include:
1,3-bis(3-aminophenoxy)benzene,
1,3-bis(4-aminophenoxy)benzene,
1,4-bis(3-aminophenoxy)benzene,
1,4-bis(4-aminophenoxy)benzene,
1,3-bis(3-aminobenzoyl)benzene,
1,3-bis(4-aminobenzoyl)benzene,
1,4-bis(3-aminobenzoyl)benzene,
1,4-bis(4-aminobenzoyl)benzene,
1,3-bis(3-amino-xcex1,xcex1-dimethylbenzyl)benzene,
1,3-bis(4-amino-xcex1,xcex1-dimethylbenzyl)benzene,
1,4-bis(3-amino-xcex1,xcex1-dimethylbenzyl)benzene,
1,4-bis(4-amino-xcex1,xcex1-dimethylbenzyl)benzene,
1,3-bis(3-amino-xcex1,xcex1-ditrifluoromethylbenzyl)-benzene,
1,3-bis(4-amino-xcex1,xcex1-ditrifluoromethylbenzyl)-benzene,
1,4-bis(3-amino-xcex1,xcex1-ditrifluoromethylbenzyl)-benzene,
1,4-bis(4-amino-xcex1,xcex1-ditrifluoromethylbenzyl)-benzene,
2,6-bis(3-aminophenoxy)benzonitrile, and
2,6-bis(3-aminophenoxy)pyridine.
Among these, particularly preferred diamines are:
1,3-bis(3-aminophenoxy)benzene,
1,3-bis(4-aminophenoxy)benzene,
1,4-bis(3-aminophenoxy)benzene,
1,4-bis(4-aminophenoxy)benzene,
1,3-bis(3-aminobenzoyl)benzene,
1,3-bis(4-aminobenzoyl)benzene,
1,4-bis(3-aminobenzoyl)benzene, and
1,4-bis(4-aminobenzoyl)benzene; and
the most preferred diamine is:
1,3-bis(4-aminophenoxy)benzene.
[More Preferred Diamine Components (2)]
Among the diamines represented by the chemical formula (4), diamines of another more preferred type are those represented by the chemical formula (4d). When these more preferred diamine components are used, it is particularly preferred to use them in a proportion of 50 to 100 mole %.
Examples of the diamines represented by the chemical formula (4d) can include:
4,4xe2x80x2-bis(3-aminophenoxy)biphenyl,
bis[4-(3-aminophenoxy)phenyl]ketone,
bis[4-(3-aminophenoxy)phenyl]sulfide,
bis[4-(3-aminophenoxy)phenyl]sulfone,
bis[4-(3-aminophenoxy)phenyl]ether,
2,2-bis[4-(3-aminophenoxy)phenyl]propane, and
2,2-bis[3-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane.
Among these, the particularly preferred diamine component is:
4,4xe2x80x2-bis(3-aminophenoxy)biphenyl.
[Tetracarboxylic Acid Dianhydride Component]
No limitation is imposed on the tetracarboxylic acid dianhydride component employed to obtain the polyimide according to the present invention, and the following illustrative tetracarboxylic acid dianhydrides can be used either singly or in combination as desired:
pyromellitic dianhydride,
3,3xe2x80x24,4xe2x80x2-biphenyltetracarboxylic acid dianhydride,
3,3xe2x80x24,4xe2x80x2-benzophenonetetracarboxylic acid dianhydride,
bis(3,4-dicarboxyphenyl)ether dianhydride,
bis(3,4-dicarboxyphenyl)sulfide dianhydride,
bis(3,4-dicarboxyphenyl)sulfone dianhydride,
2,2-bis(3,4-dicarboxyphenyl)propane dianhydride,
2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride,
1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride,
1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride,
4,4xe2x80x2-bis(3,4-dicarboxyphenoxy)biphenyl dianhydride,
2,2-bis[(3,4-dicarboxyphenoxy)phenyl]propane dianhydride,
2,3,6,7-naphthalenetetracarboxylic acid dianhydride,
1,4,5,8-naphthalenetetracarboxylic acid dianhydride,
ethylenetetracarboxylic acid dianhydride,
butanetetracarboxylic acid dianhydride,
cyclopentanecarboxylic acid dianhydride,
2,2xe2x80x2,3,3xe2x80x2-bezophenonetetracarboxylic acid dianhydride,
2,2xe2x80x2,3,3xe2x80x2-biphenyltetracarboxylic acid dianhydride,
2,2-bis(2,3-dicarboxyphenyl)propane dianhydride,
2,2-bis(2,3-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride,
bis(2,3-dicarboxyphenyl)ether dianhydride,
bis(2,3-dicarboxyphenyl)sulfide dianhydride,
bis(2,3-dicarboxyphenyl)sulfone dianhydride,
1,3-bis(2,3-dicarboxyphenoxy)benzene dianhydride,
1,4-bis(2,3-dicarboxyphenoxy)benzene dianhydride, and
1,2,5,6-naphthalenetettacarboxylic acid dianhydride.
In combination with all the kinds of the above-described tetracarboxylic acid dianhydride components, diamines in each of which some or all of the hydrogen atoms on one or more of the aromatic ring(s) have been replaced by a like number of substituent groups selected from fluoro groups, methyl groups, methoxy groups, trifluoromethyl groups and/or trifluoromethoxy groups can be used.
Further, the above-described diamines are also usable after in place of some or all of the hydrogen atoms on one or more of the aromatic ring(s) of each of the diamines, a like number of ethynyl group(s), benzocyclobuten-4xe2x80x2-yl group(s), vinyl group(s), allyl group(s), cyano group(s), isocyanate group(s), nitrilo group(s) and/or isopropenyl group(s), which can act as crosslinking points, are introduced as substituent group(s), preferably to an extent not impairing the moldability or formability. Moreover, one or more of vinylene groups, vinylidene groups and ethynylidene groups, which can act as crosslinking points, can be incorporated into each backbone skeleton, rather than as substituent group(s), preferably to an extent not impairing the moldability or formability.
These tetracarboxylic acid dianhydride components can be used either singly or in combination as needed.
Depending on the production process, tetracarboxylic acid monoanhydrides, tetracarboxylic compounds other than anhydrides, or their derivatives such as salts can also be used as desired instead of such dianhydrides.
[Preferred Tetracarboxylic Acid Dianhydride Components]
Among the above-exemplified tetracarboxylic acid dianhydride components, preferred tetracarboxylic acid dianhydrides are tetracarboxylic acid dianhydrides represented by the chemical formula (5). Specific examples can include:
pyromellitic dianhydride,
3,3xe2x80x24,4xe2x80x2-biphenyltetracarboxylic acid dianhydride,
3,3xe2x80x24,4xe2x80x2-benzophenonetetracarboxylic acid dianhydride,
bis(3,4-dicarboxyphenyl)ether dianhydride,
bis(3,4-dicarboxyphenyl)sulfide dianhydride,
bis(3,4-dicarboxyphenyl)sulfone dianhydride,
2,2-bis(3,4-dicarboxyphenyl)propane dianhydride,
2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride,
1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride,
1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride,
4,4xe2x80x2-bis(3,4-dicarboxyphenoxy)biphenyl dianhydride,
2,2-bis[(3,4-dicarboxyphenoxy)phenyl]propane dianhydride,
2,3,6,7-naphthalenetetracarboxylic acid dianhydride, and
1,4,5,8-naphthalenetetracarboxylic acid dianhydride,
[More Preferred Tetracarboxylic Acid Dianhydride Components]
Among the diamines represented by the chemical formula (5), more preferred tetracarboxylic acid dianhydrides can be:
pyromellitic dianhydride,
3,3xe2x80x24,4xe2x80x2-biphenyltetracarboxylic acid dianhydride,
3,3xe2x80x24,4xe2x80x2-benzophenonetetracarboxylic acid dianhydride,
bis(3,4-dicarboxyphenyl)ether dianhydride,
bis(3,4-dicarboxyphenyl)sulfide dianhydride,
bis(3,4-dicarboxyphenyl)sulfone dianhydride,
2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride, and
1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride.
One or more tetracarboxylic acid dianhydride components selected from the group consisting of these more preferred tetracarboxylic acid dianhydrides can be used.
[Amount of the Tetracarboxylic Acid Dianhydride Component to be Used]
The total amount of the tetracarboxylic acid dianhydride is from 0.8 to 1.25 moles per mole of the total amount of the diamine component to be used. By changing this molar ratio, the molecular weight of the resulting crosslinkable-group-containing polyimide can be controlled. A molar ratio lower than 0.8 cannot provide a molecular weight high enough to bring about sufficient properties, while a molar ratio higher than 1.25 leads to a reduction in the molecular weight.
When a dicarboxylic acid or its anhydride or derivative is used as an end blocking agent, the total amount of the tetracarboxylic acid dianhydride component may be preferably from 0.8 to 0.99, more preferably from 0.85 to 0.97 per mole of the total amount of the diamine component to be used, with a range of from 0.90 to 0.95 being most preferred.
In this case, use of a tetracarboxylic acid dianhydride component beyond the above range results in insufficient end blocking, thereby causing adverse effects on the thermal stability and moldability or formability.
When a monoamine is used as an end blocking agent, the total amount of the tetracarboxylic acid dianhydride component to be used may be preferably from 1.01 to 1.25 moles, more preferably from 1.05 to 1.20 moles per mole of the total amount of the diamine component to be used, with a range of from 1.07 to 1.15 being most preferred.
In this case, use of a tetracarboxylic acid dianhydride component below the above range results in insufficient end blocking, thereby causing adverse effects on the thermal stability and moldability or formability.
The control of the molecular weight of the crosslink-able-group-containing polyimide can be achieved by adjusting the molar ratio of the total amount of the tetracarboxylic acid dianhydride component to the total amount of the diamine component to be used. Depending on the polymerization process, the kind of the solvent, the polymerization time, the polymerization time and the like, however, their optimum charging ratio may differ in some instances.
[Crosslinkable-group-containing End Blocking Agent]
No limitation is imposed on the crosslinkable-group-containing end blocking agent to be used in the present invention. Crosslinkable-group-containing end blocking agents of various kinds are usable depending on the synthesis process of the polyimide, including monoamines and dicarboxylic acid anhydrides as representative examples. As crosslinkable group(s) to be introduced, a variety of known crosslinkable groups can be selected in accordance with molding or forming conditions.
Although no limitation is imposed on the kind of the crosslinkable group(s), representative examples can include ethynyl group, benzocyclobuten-4xe2x80x2-yl group, vinyl group, allyl group, cyano group, isocyanate group, nitrilo group, amino group, isopropenyl group, vinylene group, vinylidene group, and ethynylidene group.
[Preferred Crosslinkable-group-containing End Blocking Agents]
The crosslinkable-group-containing end blocking agent usable in the present invention may preferably be a crosslinkable-group-containing dicarboxylic acid anhydride. Depending on the synthesis process, its ring-opened product or its derivative such as its salt can be used.
Examples can include:
unsaturated aliphatic dicarboxylic acid anhydrides represented by maleic anhydride and nadic anhydride,
ethynyl-containing dicarboxylic acid anhydrides, represented by 1-phenyl-2-(3,4-dicarboxyphenyl)acetylene anhydride, ethynylphthalic anhydride and 6-ethynyl-2,3-dicarboxynaphthalene anhydride, and
phthalic acid anhydrides or 2,3-dicarboxynaphthalene anhydride derivatives containing a benzocyclo-buten-4xe2x80x2-yl group, vinyl group, allyl group or isopropenyl group.
[End Blocking Agents Containing More Preferred Crosslinking Group]
The crosslinkable group contained in the structure may preferably be an ethynyl group, with one containing a phenylethynylbenzene structure being more preferred.
[End Blocking Agents Containing Still More Preferred Crosslinking Group]
The crosslinkable-group-containing end blocking agent usable in the present invention may more preferably be a dicarboxylic acid anhydride represented by the chemical formula (3a).
Specific examples are:
1-phenyl-2-(3,4-dicarboxyphenyl)acetylene anhydride,
1-phenyl-2-(3-(3,4-dicarboxyphenoxy)phenyl)acetylene anhydride,
1-phenyl-2-(3-(3,4-dicarboxyphenylcarbonyl)phenyl)acetylene anhydride,
1-phenyl-2-(3-(3,4-dicarboxyphenylsulfonyl)phenyl)acetylene anhydride,
1-phenyl-2-(3-(3,4-dicarboxyphenylsulfinyl)phenyl)acetylene anhydride,
1-phenyl-2-(3-(2-(3,4-dicarboxyphenyl)isopropanyl)phenyl)acetylene anhydride,
1-phenyl-2-(3-(1,1,1,3,3,3-hexafluoro-2-(3,4-dicarboxyphenyl)isopropanyl)phenyl)acetylene anhydride,
1-phenyl-2-(3-(3,4-dicarboxyphenyl)phenyl)acetylene anhydride,
1-phenyl-2-(4-(3,4-dicarboxyphenyl)phenyl)acetylene anhydride,
1-phenyl-2-(4-(3,4-dicarboxyphenylcarbonyl)phenyl)acetylene anhydride,
1-phenyl-2-(4-(3,4-dicarboxyphenylsulfonyl)phenyl)acetylene anhydride,
1-phenyl-2-(4-(3,4-dicarboxyphenylsulfinyl)phenyl)acetylene anhydride,
1-phenyl-2-(4-(2-(3,4-dicarboxyphenyl)isopropanyl)phenyl)acetylene anhydride,
1-phenyl-2-(4-(1,1,1,3,3,3-hexafluoro-2-(3,4-dicarboxyphenyl)isopropanyl)-phenyl)acetylene anhydride,
1-phenyl-2-(4-(3,4-dicarboxyphenyl)phenyl)acetylene anhydride, and
2 3-dicarboxy-6-phenylethynyl)naphthalene anhydride.
The above-described, crosslinkable-group-containing end blocking agents can be used either singly or in combination. End blocking agents in each of which some or all of the hydrogen atoms on one or more of the aromatic ring(s) have been replaced by a like number of substituent groups selected from fluoro groups, methyl groups, methoxy groups, trifluoromethyl groups and/or trifluoromethoxy groups can also be used.
Further, the above-described, crosslinkable-group-containing dicarboxylic acid anhydrides are also usable after in place of some or all of the hydrogen atoms on one or more of the aromatic ring(s) of each of the anhydrides, a like number of ethynyl group(s), benzocyclobuten-4xe2x80x2-yl group(s), vinyl group(s), allyl group(s), cyano group(s), isocyanate group(s), nitrilo group(s) and/or isopropenyl group(s), which can act as crosslinking points, are introduced as substituent group(s), preferably to an extent not impairing the moldability or formability.
[Most Preferred, Crosslinkable-group-containing End Blocking Agent]
Among the above-described, crosslinkable-group-containing end blocking agents, 1-phenyl-2-(3,4-dicarboxyphenyl) acetylene anhydride is most preferred from the standpoint of the properties and practical application of the crosslinkable-group-containing polyimide according to the present invention.
[Crosslinkable-group-free End Blocking Agent]
No limitation is imposed on the crosslinkable-group-free end blocking agent usable in the present invention. Depending on the synthesis process of the polyimide, a variety of crosslinkable-group-free end blocking agents can be used. Representative examples are monoamines or dicarboxylic acid anhydrides. It is essential that a group, which may function as a crosslinking group under conditions of a molding or forming step or post-treatment step, is not contained in the structure. Examples of the crosslinking group can include ethynyl group, benzocyclobuten-4xe2x80x2-yl group, vinyl group, allyl group, cyano group, isocyanate group, nitrilo group, amino group, isopropenyl group, vinylene group, vinylidene group, and ethynylidene group.
[Preferred, Crosslinkable-group-free End Blocking Agents]
The crosslinkable-group-free end blocking agent usable in the present invention may preferably be a dicarboxylic acid anhydride. Depending on the synthesis process, its ring-opened product or its derivative such as its salt can be used.
Specific examples are:
phthalic anhydride,
4-phenylphthalic anhydride,
4-phenoxyphthalic anhydride,
4-phenylsulfinylphthallic acid,
4-phenylcarbonylphthalic acid,
4-(2-phenylisopropyl)phthalic anhydride,
4-(1,1,1,3,3,3-hexafluoro-2-phenylisopropyl)phthalic anhydride,
2,3-naphthalenedicarboxylic anhydride, and
1,8-naphthalenedicarboxylic anhydride.
The above-described dicarboxylic acid anhydrides can be used either singly or in combination. Diamines in each of which some or all of the hydrogen atoms on one or more of the aromatic ring(s) have been replaced by a like number of substituent groups selected from fluoro groups, methyl groups, methoxy groups, trifluoromethyl groups and/or trifluoromethoxy groups can also be used.
[Most Preferred, Crosslinkable-group-free End Blocking Agent]
Among the above-described dicarboxylic acid anhydrides, phthalic acid is most preferred from the standpoint of the properties and practical application of the crosslinkable-group-containing polyimide according to the present invention.
[Molar ratio of the Crosslinkable-group-containing End Blocking Agent to the Crosslinkable-group-free End Blocking Agent]
No limitation is imposed on the molar ratio of the crosslinkable-group-containing blocking agent to the crosslinkable-group-free blocking agent insofar as the ends of the synthesized crosslinkable-group-containing polyimide satisfy the conditions that xe2x80x9cthe molecule ends have crosslinking groups at 1 to 80 mole % thereofxe2x80x9d. Preferably, however, their molar ratio falls within the following range:
1/99xe2x89xa6[E1]/[E2]xe2x89xa680/20
where
[E1]: the molar quantity of the used crosslinkable-group-containing blocking agent; and
[E2]: the molar quantity of the used crosslinkable-group-free blocking agent ends.
If the value of [E1]/[E2] falls short of this range and is smaller than 1/99, no sufficient crosslinking density can be achieved, leading to insufficient improvements in chemical resistance, heat resistance and mechanical properties. If the value of [E1]/[E2] is greater than 80/20, on the other hand, a sufficient crosslinking density is available, but upon melt molding or forming, a substantial viscosity increase takes place so that the melt molding or forming becomes infeasible.
The range of the [E1]/[E2] value has to be chosen appropriately depending on molding or forming conditions. In general, however, the preferred range is:
5/95xe2x89xa6[E1]/[E2]xe2x89xa670/30,
and the more preferred range is:
10/90xe2x89xa6[E1]/[E2]xe2x89xa670/30.
The still more preferred range varies depending on the molding or forming process. For example, in a batchwise molding or forming process, such as compression molding, that involves residence in a molten state, the still more preferred range is:
30/70xe2x89xa6[E1]/[E2]xe2x89xa670/30,
and the most preferred range is:
xe2x80x8340/60xe2x89xa6[E1]/[E2]xe2x89xa660/40.
For example, in a molding or forming process, such as injection molding or extrusion, that involves residence in a molten state and requires a continuous operation, the preferred range is:
10/90xe2x89xa6[E1]/[E2]xe2x89xa650/50,
and the most preferred range is:
20/80xe2x89xa6[E1]/[E2]xe2x89xa640/60.
For example, in a molding or forming process that does not involve much residence in a molten states the preferred range is:
20/80xe2x89xa6[E1]/[E2]xe2x89xa660/40,
and the most preferred range is:
30/70xe2x89xa6[E1]/[E2]xe2x89xa650/50.
[Amount of the End Blocking Agent to be Used]
No limitation is imposed on the amount of the end blocking agent to be used, insofar as the conditions that the ends of the synthesized crosslinkable-group-containing polyimide satisfy the conditions that xe2x80x9cthe molecule ends have crosslinking groups at 1 to 80 mole % thereofxe2x80x9d.
However, the end blocking agent may be used in an amount that satisfies preferably the following range:
([Dc]xe2x88x92[Ma])/([Da]xe2x88x92[Tc]) greater than 2,
more preferably the following range:
20 greater than ([Dc]xe2x88x92[Ma])/([Da]xe2x88x92[Tc]) greater than 3
where
[Da]: total amount of the diamine component (mol),
[Tc]: total amount of the tetracarboxylic acid dianhydride component (or its ring-opened product or derivative) (mol),
[Ma]: total amount of the monoamine component to be used as an end blocking agent (mol), and
[Dc]: total amount of the dicarboxylic acid anhydride component (or its ring-opened product or derivative) to be used as an end blocking agent (mol).
If the value of ([Dc]xe2x88x92[Ma])/([Da]xe2x88x92[Tc]) falls short of this range and is smaller than it, no sufficient blocking of molecule ends is feasible, resulting in deteriorations in thermal stability, thermal oxidation stability, and moldability or formability. If the value exceeds the above range, on the other hand, it becomes difficult to control the molecular weight and also to wash off any extra portion of the end blocking agent.
[Production Process of the Crosslinkable-group-containing Polyimide]
The polyimide can be obtained by providing the above-described raw materials and conducting polymerization and imidation by known methods. Although no limitation is imposed on the production process, the polymerization is generally conducted in a solvent.
Examples of the process can generally include:
A) a process which comprises stirring a diamine component and a tetracarboxylic acid dianhydride component in a solvent to obtain a crosslinkable-group-containing polyamic acid and then thermally or chemically conducting its dehydrating imidation, and
B) a direct polymerization process which comprises directly heating a diamine component and a tetracarboxylic acid dianhydride component in a form dissolved or suspended in a solvent such that dehydrating imidation is thermally effected.
[Polymerization Solvent]
Examples of the solvent can include:
m) Phenol solvents:
Phenol, o-chlorophenol, m-chlorophenol, p-chlorophenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, and 3,5-xylenol;
n) Aprotonic amide solvents:
N,N-Dimethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidine, N-methylcaprolactam, and hexamethylphosphorotriamide;
o) Ether solvents:
1,2-Dimethoxyethane, bis(2-methoxyethyl)ether, 1,2-bis(2-methoxyethoxy)ethane, tetrahydrofuran, bis[2-(2-methoxyethoxy)ethyl]ether, and 1,4-dioxane;
p) Amine solvents:
Pyridine, quinoline, isoquinoline, xcex1-picoline, xcex2-picoline, xcex3-picoline, isophorone, piperidine, 2,4-lutidine, 2,6-lutidine, trimethylamine, triethylamine, tripropylamine, and tributylamine; and
q) Other solvents:
Dimethyl sulfoxide, dimethyl sulfone, diphenyl ether, sulphorane, diphenyl sulfone, tetramethylurea, anisole, and water.
These solvents can be used either singly or in combination. Each of these solvents can also be used by mixing it with one or more of solvents to be described subsequently herein under r), s), t) and u). When used as a mixture, it is not absolutely necessary to choose solvents in such a combination that allows the solvents to be mutually dissolved at a desired ratio, and no problem or inconvenience arises even if they cannot be mixed or their mixture is not homogeneous.
[Polymerization Concentration]
Absolutely no limitation is imposed on the concentration at which polymerization is to be conducted in such a solvent. Expressing the proportion of the total weight of the whole diamine component and the whole tetracarboxylic acid dianhydride component in terms of percentage on the basis of the total weight of the whole solvent, the whole diamine component and the whole tetracarboxylic acid dianhydride component, the preferred polymerization concentration is from 5 to 50%, with 10 to 30% being more preferred.
[Charging Order]
No limitation is imposed on the order in which the diamine component, the tetracarboxylic acid dianhydride component and the end blocking agent are charged when the diamine component, the tetracarboxylic acid dianhydride component or the end blocking agent consists of two or more kinds of diamines, dianhydrides or blocking agents, they can be added in an arbitrary order. It is also discretionary to add each component or agent at once or in portions.
[Polymerization Conditions]
No particular limitation is imposed on the polymerization temperature, polymerization time or polymerization pressure. Known conditions can be applied.
The polymerization temperature may generally be in a range of from xe2x88x9210xc2x0 C. to 10xc2x0 C. in the case of the polymerization of the crosslinkable-group-containing polyamic acid, and is a range of from 50xc2x0 C. to 250xc2x0 C. in the case of the imidation. The reaction time may generally be from 1 to 48 hours, although it differs depending on the kinds of the monomers to be used, the kind of the solvent to be employed or the kind of the reaction temperature to be employed. Further, as the reaction pressure, atmospheric pressure is sufficient.
[Logarithmic Viscosity Number of Crosslinkable-group-containing Polyamic Acid]
When polymerization is conducted through a crosslink-able-group-containing polyamic acid, the logarithmic viscosity number of the crosslinkable-group-containing polyamic acid may preferably be in a range of from 0.1 to 2.0 dL/g (as measured at a concentration of 0.5 g/dL and 35xc2x0 C. in N,N-dimethylacetamide). A logarithmic viscosity number smaller than 0.1 leads to a decrease in the molecular weight between crosslinking points so that mechanical properties are lowered significantly, whereas a logarithmic viscosity number greater than 2.0 leads to an increase in melt viscosity so that melt moldability or formability is reduced substantially. The preferred logarithmic viscosity number is in a range of from 0.3 to 1.2, with a range of from 0.4to 0.7 being more preferred.
[Chemical Imidation]
Chemical imidation is a process to chemically effect dehydration by reacting the crosslinkable-group-containing polyamic acid with a dehydrating agent having hydrolytic ability.
Usable examples of the dehydrating agent can include aliphatic carboxylic acid anhydrides represented by acetic anhydride and trifluoroacetic anhydride; phosphoric acid anhydrides represented by polyphosphoric acid and phosphorus pentoxide; mixed acid anhydrides of these acids; and acid chlorides led by chloromethanesulfonic acid, phosphorus pentoxide and thionyl chloride. These dehydrating agents can be used either singly or in combination. These dehydrating agents can be used in an amount of 2 to 10 moles, preferably 2.1 to 4 moles, per mole of the whole amount of the diamine component to be used.
Further, chemical imidation can also be conducted in the presence of a base catalyst. As the base catalyst so used, the amine solvents mentioned above under p) can be mentioned. In addition, organic bases such as imidazole, N,N-dimethylaniline and N,N-diethylaniline as well as inorganic bases such as potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium hydrogencarbonate and sodium hydrogencarbonate can be mentioned. These catalysts can be used in an amount of from 0.001 to 0.50 mole, preferably from 0.05 to 0.2 mole, per mole of the whole amount of the diamine component to be used.
No particular limitation is imposed on the reaction temperature, reaction time and reaction pressure for the chemical imidation process, and known conditions can be applied. Described specifically, the reaction temperature may preferably be from xe2x88x9210xc2x0 C. to around 120xc2x0 C., with a range of from around room, temperature to 70xc2x0 C. being more preferred. It is room temperature that is most preferable and practical from the standpoint of practice. On the other hand, the reaction time may preferably be from about 1 to 24 hours although it differs depending on the kind of the solvent to be used and other reaction conditions. More preferably, the reaction time may be from 2 to around 10 hours. As the reaction pressure, atmospheric pressure is sufficient. As the atmosphere, air, nitrogen, helium, neon or argon is usable, and no particular limitation is imposed thereon. Preferably, however, nitrogen or argon which is an inert gas is chosen.
[Thermal Imidation]
Thermal imidation can be achieved by heating polyamic acid or its solution generally to 100xc2x0 C. to 300xc2x0 C.
The thermal imidation can also conducted in the concurrent presence of a similar base catalyst as that employed in the chemical imidation process.
No particular limitation is imposed on the reaction temperature, reaction time and reaction pressure for the thermal imidation process, and known conditions can be applied. Described specifically, as the reaction temperature, 80xc2x0 C. to around 400xc2x0 C. can be used, with a range of from 100xc2x0 C. to around 300xc2x0 C. being preferred. On the other hand, the reaction time may preferably be from 0.5 to 24 hours although it differs depending on the kind of the solvent to be used and other reaction conditions. As the reaction pressure, atmospheric pressure is sufficient. As the atmosphere, air, nitrogen, helium, neon or argon is usable, and no particular limitation is imposed thereon. Preferably, however, nitrogen or argon which is an inert gas is chosen.
[Combined Use of Chemical Imidation and Thermal Imidation]
Chemical imidation and thermal imidation can be used in combination.
Illustrative are:
A) a process in which heating is also conducted at the same time upon practice of the above-described chemical imidation process, and
B) a process in which upon conducting the above-described thermal imidation process, a dehydrating agent useful in chemical imidation is caused to exist concurrently.
[Direct Polymerization Process]
The term xe2x80x9cdirect polymerization processxe2x80x9d as used herein means a process which comprises directly heating a diamine component and a tetracarboxylic acid dianhydride component in a form dissolved or suspended in a solvent such that dehydrating imidation is thermally effected. This direct polymerization is achieved by conducting polymerization and imidation in a solvent in a similar manner as in thermal imidation.
Like the chemical imidation process, the direct polymerization process can also be conducted in the concurrent presence of a base catalyst. Usable base catalysts and their amount to be used are the same as those described above in connection with the chemical imidation process.
Further, to take out of the system water which is to be formed by the dehydrating imidation reaction, it is also possible to make another solvent exist at the same time. Solvents which are usable here can include:
r) benzene, toluene, o-xylene, m-xylene, p-xylene, chlorobenzene, o-dichlorobenzene, m-dichlorobenzene, p-dichlorobenzene, bromobenzene, o-dibromobenzene, m-dibromobenzene, p-dibromobenzene, o-chlorotoluene, m-chlorotoluene, p-chlorotoluene, o-bromotoluene, m-bromotoluene, and p-bromotoluene.
These solvents can be used either singly or in combination. Each of these solvents can also be used by further mixing it with one or more of the solvents described above under m) to q) and the solvents to be described subsequently under s) to u). When used as a mixture, it is not absolutely necessary to choose solvents in such a combination that allows the solvents to be mutually dissolved at a desired ratio, and no problem or inconvenience arises even if they cannot be mixed or their mixture is not homogeneous. Absolutely no limitation is imposed on the amount of the dehydrating agent to be used.
No particular limitation is imposed on the reaction temperature, reaction time and reaction pressure, and known conditions can be applied. Described specifically, as the reaction temperature, 100xc2x0 C. to around 300xc2x0 C. can be applied, with a range of from 120xc2x0 C. to around 250xc2x0 C. being preferred. On the other hand, the reaction time may generally be from 0.5 hour to 24 hours although it differs depending on the kind of the solvent to be used and other reaction conditions. As the reaction pressure, atmospheric pressure is sufficient. As the atmosphere, air, nitrogen, helium, neon or argon is usable, and no particular limitation is imposed thereon. Preferably, however, nitrogen or argon which is an inert gas is chosen.
[Treatment of the Crosslinkable-group-containing Polyimide]
The crosslinkable-group-containing polyimide can be improved in chemical resistance, heat resistance, mechanical properties and the like by subjecting it to intermolecular crosslinking through its treatment during or after its molding or forming.
Conditions for such a crosslinking reaction are not limited and can be set as desired. Further, these conditions significantly vary depending on the kind and quantity of crosslinkable groups to be used.
When crosslinkable-group-containing molecule ends are represented by the chemical formula (2a), for example, the preferred crosslinking method is heat treatment, and by the heat treatment, carbon-carbon triple bonds are thermally caused to react so that crosslinks are formed between molecular chains.
[Conditions for the Heat Treatment]
When crosslinkable-group-containing molecule ends are represented by the chemical formula (2a), the temperature, time and pressure of the heat treatment are not particularly limited, and are determined depending on properties required for a crosslinked thermoplastic polyimide to be obtained. As the temperature of the heat treatment, 250xc2x0 C. to around 450xc2x0 C., preferably 300xc2x0 C. to around 400xc2x0 C. can be applied, with 330xc2x0 C. to around 380xc2x0 C. being most preferred from the standpoint of practice. At a temperature lower than 250xc2x0 C. the crosslinking reaction hardly takes, while at a temperature higher than 450xc2x0 C., polyimide backbones undergo modifications so that their properties cannot be obtained sufficiently.
Although the time of the heat treatment differs depending on the other conditions for the heat treatment, it may be preferably 0.1 hour or longer, more preferably 0.2 hour or longer, and the most preferred time is 1 hour or longer.
A heat treatment time shorter than this time results in an insufficient crosslinking density, thereby practically failing to observe improvements in physical properties.
On the other hand, an excessively long crosslinking time is disadvantageous from the standpoint of the process efficiency, and depending on the backbone structure, there is a potential problem of modifications. The upper limit of a preferred heat treatment time is 100 hours.
As the pressure for the heat treatment, atmospheric temperature is sufficient. If necessary, however, it is also possible to adopt such a process that heat treatment is effected while conducting degasfication or the like under elevated pressure.
As the atmosphere, air, nitrogen, helium, neon or argon is usable, and no particular limitation is imposed thereon. Preferably, however, nitrogen or argon which is an inert gas is chosen.
[Heat Treatment Method]
The heat treatment method differs depending on the form of a crosslinkable-group-containing polyimide, and no limitation is imposed thereon. When a crosslinkable-group-containing polyimide obtained, for example, in the form of powder or granules is used, examples of its heat treatment method can include:
A) to subject it, as is, to heat treatment;
B) to apply melt molding or forming to obtain a molded or formed product shaped as desired, and then to subject the molded or formed product to heat treatment;
C) to simultaneously conduct heat treatment while applying melt molding or forming; and
D) to conduct its heat treatment, as is, to an intermediate extent, then to apply melt molding or forming to obtain a molded or formed product shaped as desired, and thereafter to subject the molded or formed product to heat treatment again.
As their applications, the followings are possible, respectively:
A) as a crosslinked thermoplastic polyimide is obtained in the form of powder or granules, it can be added, as is, as a filler to other resins or can be formed, as is, into a molded product by sinter molding;
B) all general melt molding or forming;
C) Forming of films or sheets especially by pressing, and their use as adhesives; and
D) All general melt molding or forming, especially forming of films or sheets by pressing and their use as adhesives.
[Treatment Methods Other Than Heat Treatment]
Instead of heat treatment, various energy sources which induce crosslinking can be used. Illustrative are irradiations of visible light, ultraviolet rays, ultraviolet rays, radiations such as xcex1-, xcex2- and xcex3-rays, electron beams, and X-rays, and further, plasma treatment and doping treatment.
[Crosslinking Promoter and Crosslinking Retarder]
A crosslinking promoter or crosslinking retarder can be used to control the crosslinking reaction velocity. No limitation is imposed on the crosslinking promoter or crosslinking retarder. A compound which, when used together with a crosslinkable-group-containing polyimide, can sub-stantially promote or retard the crosslinking reaction, can be used in combination as desired.
It is possible to add, for example, a metal catalyst containing gallium, germanium, indium or lead, a transition metal catalyst containing molybdenum, manganese, nickel, cadmium, cobalt, chromium, iron, copper, tin, platinum or the like, a phosphorus compound, a silicon compound, a nitrogen compound, or a sulfur compound.
[Solution or Suspension Containing a Crosslinkable-group-containing Polyimide]
A solution or suspension which contains a crosslink-able-group-containing polyimide according to the present invention can be used in a pre-treatment step of shaping or melt molding or forming of the crosslinkable-group-containing polyimide.
The solution or suspension can be prepared using a solvent which does not cause a chemical reaction with the crosslinkable-group-containing polyimide according to the present invention.
Usable examples of the solvent can include, in addition to the solvent described above under m) to q) and r), the followings:
s) Acetone, methyl ethyl ketone, methyl isobutyl ketone, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, pentane, hexane, heptane, cyclohexane, dichloromethane, chloroform, carbon tetrachloride, fluorobenzene, methyl acetate, ethyl acetate, butyl acetate, methyl formate, and ethyl formate;
t) Water, the amine solvents described above under p), imidazole, N,N-dimethylaniline, N,N-diethylaniline, and aqueous solutions containing potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium hydrogencarbonate, and sodium hydrogencarbonate, respectively; and
u) Silicone oil, machine oil, working oil, kerosine, gasoline, and jet fuel.
These solvents can be used either singly or in combination. They can also be used by further mixing them with one or more of the solvents described above under m) to r). When used as a mixture, it is not absolutely necessary to choose solvents in such a combination that allows the solvents to be mutually dissolved at a desired ratio, and no problem or inconvenience arises even if they cannot be mixed or their mixture is not homogeneous. The concentrations of the aqueous solutions described above under t) are not limited and can be determined as desired. In general, their concentrations are in a range of from 1 to 60%.
No limitation is imposed on the preparation method of the solution or suspension which contains the polyimide according to the present invention, and all known methods are applicable.
Illustrative preparation methods can include:
A) to use, as is, a solution or suspension after completion of polymerization; and
B) to obtain the crosslinkable-group-containing polyimide in the form of powder, granules or a block, and then to dissolve or disperse it in the above-described solvent.
No limitations are imposed on the preparation conditions, such as temperature, time and stirring method, upon preparation of the solution or suspension. In the case of the suspension, no limitation is imposed on the particle size or particle size distribution of powder, granules or the like to be dispersed, and upon preparation, a dispersion promoter or an emulsifier can also be added.
[Alloys and Blends With Other Resins]
In accordance with the application purpose of the crosslinkable-group-containing polyimide according to the present invention, it can be blended or alloyed, to an extent not impairing the object of the present invention, with suitable amount or amounts of one or more of resins such as thermoplastic resins, for example, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polybutadiene, polystyrene, polyvinyl acetate ABS resin, polybutylene terephthalate, polyethylene terephthalate, polyphenylene oxide, polycarbonates, PTFE, celluloid, polyarylates, polyether nitrites, polyamides, polysulfones, polyether sulfones, polyether ketones, polyphenyl sulfide, polyamide-imides, polyether imides, modified polyphenylene oxide and polyimides, and thermosetting resins, for example, thermosetting polybutadiene, formaldehyde resins, amino resins, polyurethane, silicone resins, SBR, NBR, unsaturated polyesters, epoxy resins, polycyanates, phenol resins and polybismaleimide. No particular limitation is imposed on their blending or alloying method, and a known method can be applied.
[Fillers and Additives]
With the crosslinkable-group-containing polyimide according to the present invention, various fillers or additives can be mixed to extents not impairing the object of the present invention. Their examples can include abrasion resistance improvers such as graphite, carborundum, silica powder, molybdenum disulfide and fluorinated resins; electrical characteristics improvers such as clay and mica; anti-track property improvers such as asbestos, silica and graphite; acid resistance improvers such as barium sulfate, silica and calcium metasilicate; thermal conductivity improvers such as iron powder, zinc powder, aluminum powder and copper powder; and further, glass beads, glass balls, talc, diatomaceous earth, alumina, Shirasu (white volcanic ash) balloons, alumina hydrate, metal oxides, colorants, and pigments. No particular limitation is imposed on the mixing method, and a known method can be applied.